1. Field of the Invention
The present invention generally relates to an engine exhaust system for a vehicle.
2. Background Information
Conventionally, a flexible coupling such as a spherical joint used in an exhaust system of a vehicle performs a vibration damping function by preventing transmission of vibrations from the engine to the exhaust system or preventing vibrations caused by resonance in the exhaust system being transmitted to the engine. Accordingly, the spherical joint plays an important role in reducing vibrations transmitted to a vehicle body via the mounts of the exhaust system and the engine system.
An engine exhaust system for a vehicle using a spherical joint has been applied to a front exhaust engine as shown in FIG. 7 of the drawings hereof, an example being disclosed in Japanese Unexamined Patent Publication No. 2002-371841, and to a rear exhaust engine as shown in FIGS. 8 and 9 of the drawings hereof, an example being disclosed in Japanese Unexamined Patent Publication No. 10-196358.
In the present specification, the terms ‘front’ and ‘rear’ and ‘forward’ and ‘rearward’ relate to the forward direction of travel of a vehicle. For example ‘front exhaust’ and ‘rear exhaust’ refer to the position of the exhaust manifold with respect to a transversely-mounted engine. The invention is not, however, limited to use in transverse-engine vehicles.
In the abovementioned conventional engine exhaust systems, it is necessary to arrange spherical joints in a particular way depending on their number, mounting location, and mounting angle. If vibrations of the exhaust system are to be absorbed effectively, the spherical joints must allow movement in the direction of the vibration. However, layout restrictions make it difficult to arrange the spherical joints in such a way that they can effectively absorb the vibrations. Where the spherical joints cannot be mounted in ideal locations and orientations due to a layout restriction, it is difficult to obtain satisfactory vibration damping performance.